Brake fluid



NlTED STATES PATENT OFFICE 2.020.543 I BRAKE rwm.

Eranklin Phineas Frey, Cleveland, Okla, assi nor to Johnson Oil Refining Company, Chicm. Ill, a corporation of Delaware No Drawing. Application January 2, 188 5, Serial No. 106

3-Claims. (61. 252-5) This invention relates to fluid operated brake factory. The ethyl-acetate has a very low cosystems and particularly to the character 01 the eiiicient oi viscosity which varies very slightly liquid used in such systems. within the temperature degree range encountered 5 The desired characteristic of liquids of this by the brake fluid and serves as a means for balcharacter are that they shall retain a relatively ancing or offsetting the variation in viscosity high viscosity at the high temperatures encounof the castor oil at the lower temperatures. tered in the summer time so that it is not difii- The proportions may be varied within reasoncult to avoid leakage past the pistons in the able ranges-to accommodate the difierent temvarious cylinders 01 the system. Furthermore, peratures encountered-as for example, in very the viscosity'oi the liquid must be such as to perlow temperatures it follows that the full propormit free flow at the extreme low temperatures tion of ethyl-acetate specified namely 60% would to which the braking system is subjected. be advisable. while in high temperatures where The ideal liquid would, of course, be one havthe viscosity of the castor oil is comparatively ing substantially the same viscosity characterislow. the lesser amount or ethyl-acetate could be u tics from a low temperature of around iorty deused. grees below zero to a maximum temperature of While the above solution is particularly adaptone hundred twenty degrees above zero. 'but able for use in brake cylinders of fluid operated such a liquid is very diiiicult to obtain. It is brake systems, it is also 0! considerable value also a requirement or the brake liquid that it for use in such devices as shock absorbers and 20 shall have suilicient lubricating value as to luthe like, and obviously the claims are intended bricate the pistons in their movement in the to cover such similar devices. cylinder. Having thus described the invention. what is It is the object of the present invention to claimed as new and desired to be secured by Letprovide liquid for use in fluid operated brake ters Patent is: 25

- systems which wfll tulflll as nearly as possible i. A liquid for use in cylinders of fluid operthe above enumerated requirements. ated brake systems and the like consisting 0! Applicant has discovered that a solution of castor oil and ethyl-acetate. ethyl-acetate and castor oil when combined in 2. A liquid for usein cylinders of fluid operthe proper proportions, provides a liquid which ated brake systems and the like consisting 0! 30 is quite satisfactory in iulfliling the requireethyl-acetate and castor oil in which the volume ments enumerated above. of ethyl-acetate is greater than that of the caster While the exact proportions are not absolutely oil- V essential, applicant has obtained the best re- 3. A liquid for use in cylinders of fluid opersultswith a solution of this character wherein ated brake systems and the like consisting of a there is more ethyl-acetate by volume than 'casa solution 0! approximately forty per cent castor oil. For example, it has been found that a tor oil and approximately sixty per cent ethylsolution, containing substantially 40% castor oil acetate.

and ethyl acetate by volume, is most satis- FRAN PHINEAB 

